Art of making leaf metal.



UNITED STATES PATENT FFICE.

FRIEDRICH HAENLE, OF PASING, GERMANY.

ART OF MAKING LEAF METAL.

SPEGIFIUATIGN forming part of Letters Patent No. 699,920, dated May 13, 1902.

Application filed September 1, 1900. $erial No. 28,828 (No specimens.)

T0 at whom it may concern.-

Be it known that I, FRIEDRICH HAENLE,a subject of the German Emperor, residing at Pasing, near Munich, Germany, have invented certain new and useful Improvements in the Art of Making Leaf Metaltl1at is, thin leaves of gold or silver or of any other suitable metal-of which the following is a specification. I

In the art of making leaf metal as heretofore practiced the metal is first reduced to thin sheets by rolling or hammering, or both. Sometimes the sheets of metal are further spread and reduced in thickness by piling them with alternate sheets of parchment or vellum and subjecting the pile or mold to a hammering process. In this way the metal may be made quite thin; but parchment and vellum do not possess the properties which are necessary for the reduction of metal to the thinness of the product known as leaf metal. Leaf metal proper has always been produced by assembling the thin sheets between gold-beater skins and hammering the pile thus formed to spread the metal. The metal may be beaten several times in this way, the large sheets from the first beatingbetween skins being cut usually into four parts and placed between skins for a second beating, &c.

The term leaf metal is used in this specification to designate the very thin or attenuated leaves of metal which are too frail to be beaten in vellum or parchment and which have only hitherto been beaten in gold-beater skins.

The gold-beater skins hitherto employed are expensive and necessarily of very limited size. The expense of the skins is partly due to the method of preparing them and partly due to the fact that when first used their product is a second grade, and they must be used for a considerable period of time before they are adapted to produce a fine grade of leaf metal, particularly of leaf metal made from the baser metals, such as brass. Thus before gold-beater skins are suitable for boating the baser metals they must be used for one or two years for beating gold or about a year for beating silver. During the first few weeks of use they do not even give perfect results in beating pure gold or silver. In addition to the great cost of gold-beater skins a large item of expense is due to the fact that they are easily injured or destroyed.

I have discovered that a certain paper, the so-called Pergamyn paper and papers of similar structure, may be used in beating leaf metal in lieu of gold-beater skins. This paper is not only much cheaper than the goldbeater skins, but it is better-suited for this purpose, producing leaf metal of better finish and more uniform texture. The Pergamyn paper is especially valuable in the beating of metals by machinery, as it works perfectly under a power-hammer, whereas when goldbeater skins are used the beating-machine must be frequently stopped to permit the package of leaf and skins to cool. The same heating takes place in beating gold with paper; but in the case of paper the heating is advantageous, as it causes the metal to yield or spread more rapidly and the paper is not injured by the heat, whereas the skins when hot deteriorate and also retard the spreading of the metal. The pile of sheets of metal and Pergamyn paper may be beaten by machinery or by hand in the usual manner.

The Pergamyn paper, which Iprefer to use, is manufactured substantially as follows: A suitable quantity of cellulose produced by inindirect boiling (following the system of Mitscherlich) or in any other suitable and desired manner is mixed with glue and alum in proper proportions and this mixture subj ected to the action of suitable beating or disintegrating and mixing apparatus until the fiber is scarcely visible and the mass is of a gelatin-like consistency and has a glassy appearance. The material prepared as above indicated is then rolled into sheets and dried by paper-making machinery in the ordinary manner. This paper is made in difierent thicknesses and weights.

As above stated, lam aware that various materialssuch as parchment, vellum, and some papers have been used in the early stages of beating metal; but I believe myself to be the first to use paper in lieu of goldbeater skins in the beating of leaf metal. It is to be understood, therefore, that my invention relates to the final steps in the manufac-' ture of leaf metal-that is, to the steps in Pergamyn,0rsubstantially similar paper, 10 which the metal is reduced to extreme thinand then beating the sheets so assembled in ness. the usual manner.

WVhat I claim as my invention, and desire In witness whereof I have hereunto set my 5 to secure by Letters Patent, ishand in presence of two Witnesses.

The improvement in the art of beating gold FRIEDRICH HAENLE. andother metals into leaf metal which con- \Vitnesses: sists in assembling the sheets of metal, for HCH. KACHEL,

the final beatings, with alternate sheets of] GEORGE I BURNS. 

